[unreadable] [unreadable] Infection with HPV16 is strongly associated with squamous cell carcinoma of the oropharynx (SCCOP) and is detected in approximately 50% of these tumors. In a small study of patients with squamous cell carcinomas of the head and neck as well as studies of women with cervical cancer, detection of HPV16 DNA in peripheral blood appears to be a predictor of tumor recurrence. Larger studies from several institutions have utilized a similar concept with significant success in patients with nasopharyngeal carcinoma. In these studies, the presence of EBV DNA in the sera of patients was an indicator of recurrence or metastasis. Furthermore, viral DNA load can be an earlier indicator of recurrence than clinical exam or imaging. It is our hypothesis that the presence of HPV16 in peripheral blood of SCCOP patients will be an early indicator of recurrent disease and in particular distant metastatic disease. To test this hypothesis, we will recruit 188 patients with SCCOP and determine via real-time PCR whether the patients have detectable HPV16 E6 or E7 DNA in their sera both before and after treatment. Follow-up (including timing, frequency, imaging, and blood work) will be determined by the treating clinicians. Blood will be obtained approximately 6 weeks after completion of radiotherapy and approximately every 6 months for 3 years (greater than 90% of recurrences will occur within 3 years of treatment). The final goal of this project is to expand on an existing pilot study of HPV16 and SCCOP funded by our institutional research funds to investigate whether the presence of HPV16 in peripheral blood of SCCOP patients will be an early indicator of clinical outcome of the disease. By using HPV16 DNA in sera as a disease marker in patients with SCCOP we may determine which patients are at high risk for disease recurrence/metastasis they may have significant implications for the development of tailored treatment or prevention of recurrent or metastatic disease, and potentially enrolled in experimental protocols for more aggressive systemic management. Secondly, in follow-up such a marker may have utility in earlier detection of recurrent disease, which at present has an extremely poor prognosis. [unreadable] [unreadable] [unreadable]